Introduction

How does music relate to the lyrics? It is tempting to think that a song tries to convey some feeling or emotion, and that both the music and lyrics are there to support this message. Let me give you an example. We might expect a song with a slow beat and laid back guitar to talk about laid back topics, maybe a trip to the beach. At the other end of the spectrum, heavy metal would likely concern itself with darker, heavier subjects. However, are these suspicions even true? Let’s put some numbers to the hypothesis that there in fact is a relationship between music and lyrics. In the next sections I’ll take you through a journey where we approach this topic with a statistical mindset, harnessing all the powers that modern technology has to offer along the way.

We’ll start out with picking a large body of music and for each track in there, we are going to collect and store the lyrics. It would be way too cumbersome to scrape all the lyrics from the internet myself, but fortunately the Musixmatch API allows querying lyrics from code in a single API call. For an unpaid account only 30% of the lyrics for a queried track is returned, but that will do for our intents and purposes. I assign every set of lyrics a sentimental, or valency, score automatically using the NLTK package, which offers natural language processing functionalities. A low score indicates a sad feeling, whereas a high score a happy feeling. When the lyrics have a numerical score we can start to answer our question: how does music relate to lyrics?

The research question is still a bit broad. We settled on how to analyze lyrics, but not yet on which aspects on music we’ll focus. We are going to keep the research broad, and explore how the lyrics relate to the four main elements of music, that is melody, harmony, instrumentation and rhythm. To access and preprocess the music properties the Spotify API is used. We will investigate each separately, and in the end combined.

Let us dive into it!

Corpus

The first order of business is choosing the corpus of music. We have chosen a broad research question and the corpus should reflect this. It must draw inspiration from various genres and contain a large number of songs, only then can we justify general conclusions. Because the heavy lifting in terms of fetching the data we need is done by the Musixmatch and Spotify APIs, this is most certainly possible.

The exhaustive list of albums that are included in this research:

Elephant, Madvillainy, ..Like Clockwork, Street Worms, Midnights, HEROES & VILLAINS, St. Elsewhere, The White Album, Plastic Beach, Demon Days, Thriller, In the Aeroplane Over the Sea, Hawaii: Part ||, WHEN WE ALL FALL ASLEEP, WHERE DO WE GO?, Dua Lipa, The Money Store, OFFLINE!, OK Computer and Rumours

This totals over 280 tracks and 16 hours of listening time.

Playlist

Discovery

The Spotify API offers functionalities that range from very high to very low level. Here we will use some the the high level analyses like valence and energy to learn about the corpus.

When we plot energy, musical and lyrical valence values against each other we find something enormously interesting. Clearly, even though energy and valence do not seem related, musical and lyrical valence appear highly correlated.

Melody

Intuitively, it would appear that melody encodes a lot of the valency information of a song. The melody is usually the most memorable part and often indicative of the feel of a song. So it makes sense to look at the melody of two tracks, one with low and one with high lyrical valence. A visualization tool that makes sense to use, is a chromogram. This captures for each moment the notes that are played, as analyzed using the fourier transform. Let’s try this and see if any melody lines become apparent.

Unfortunately, looking at the chromograms, no discernible melody is recognizable. The only thing that sticks out is the droning ‘E’ in Ball and Biscuit, but this could hardly be called a melody. It appears we need a different tool.

Melody: What is the happiest key?

Though finding specific melodies is a difficult task to automatize, we could look at the key in which the melody is played.

Harmony

The troubles with key matching.

Harmony: Modulations

Instrumentation

Rhythm

Note!

I’m redesigning my entire project to fit my research question, as I’m getting the hang of all the R functionalities. This means I’m currently retailoring all previous homework assignments!